U.S. Pat. No. 3,545,619 relates to a water treatment plant comprising a separator. This separator has a first reservoir with an inlet and a second reservoir with an outlet. The first reservoir is a settling reservoir for separation of major impurities and comprises a settling device consisting of inclined tubes. The second reservoir is divided into a first portion containing a filter and a second portion containing a dewatering device. The two portions of the reservoir communicate with each other. The filter is placed at the transfer from the first portion to the second portion. A perforated pipe leads rain water from the first reservoir to the second reservoir. This plant is not very compact.
French patent publication No 2729168 relates to an assembly for rain water recovery and recycling. It discloses a separator for removing impurities, especially smaller particles, from rain water. The separator comprises a first reservoir having an inflow and a second reservoir having an outflow; the first reservoir performs the function of removing the heaviest portions of the impurities. These particles fall onto the bottom of the first reservoir due to gravity. At least part of them stay in the second reservoir because of a filter located over the bottom of the first reservoir; the second reservoir is divided into a first chamber and a second chamber, said chambers communicating with each other and the first chamber being provided with a filter. This assembly is rather complicated and the filtering qualities not quite satisfactory.
The object of the invention is to provide a separator structure which is more compact than the known separators and which has better filtering qualities.